Device in a frame plate for a plate heat exchanger

ABSTRACT

A frame plate (11) for a plate heat exchanger has two ports (12, 13), to which there are connected two tubes provided with annular flanges (16, 17). The ports (12, 13) are situated so close to each other that there is no room for the flanges (16, 17) of the two tubes to be arranged side by side. The problem is solved, according to the invention, by arranging at least one port (12), between the frame plate (11) and the annular tube flange (16), at least one removable spacing member (14) surrounding a communication channel between the port (12) and the interior of the tube, the tube flange (16), further, being connected with the frame plate (11) by means (18) separate from the spacing member (14) in a manner such that the latter is clamped between the frame plate (11) and the tube flange (16).

The present invention relates to a device in a frame plate for a plateheat exchanger, wherein two tubes provided with annular flanges andintended for heat exchanging media are connected with the frame platesuch that the interior of each tube is in communication with arespective port in the frame plate, the distance between the centres ofthe ports, seen in the plane of the outer side of the frame plate, beingsmaller than the sum of the outer radii of the tube flanges and,therefore, the tube flanges being arranged at different distances fromthe frame plate.

A plate heat exchanger consists basically of a package of heat exchangeplates, which are held together between one fixed and one movable frameplate. The heat exchange plates have a number of ports situated alignedwith each other, such that the ports together form inlet and outletchannels through the plate package for two heat exchanging media.Usually the ports in each plate, for instance four, are arranged inpairs, two at the top and two at the bottom of the plate.

For each pair of ports in the heat exchange plates, there is acorresponding pair of ports provided in a frame plate, which latterports are connected to two tubes for transfer of the heat exchangingmedia. The tubes are attached to the frame plate by means of annularflanges arranged at the tube ends. The tube flanges can either be weldeddirectly on the tubes or loosely fitted around them and abutting againstsmaller stop flanges, which are fixed to the tube ends.

It has proved that at certain small heat exchangers, having a width ofonly a few decimeters, there has been a problem that the ports in theframe plate are situated so close to each other, that there is no roomfor a side by side arrangement of the tube flanges of the connectingtubes.

In a known device (see FIGS. 1 and 2), which solves the above-mentionedproblem, the tube connections have been arranged such that the tubeflanges are situated at different distances from the frame plate.Hereby, the tube flanges can overlap each other radially withoutinterference. The known device comprises a joint pipe, which has anannular flange at one end adapted to be connected to a tube flange, andwhich is fixed at its other end, for instance welded to the frame plate.

In spite of the fact that the known device in a seemingly simple waysolves the above described problem, it is associated with certaindrawbacks making it expensive to produce. One drawback is that theconsumption of expensive material is large. Since the kind of heatexchangers here concerned is mainly intended for aggressive media, thejoint pipe and its flange must be made of an expensive, stainlessmaterial, usually stainless steel or titanium. Further, the joint pipemust be able to resist strains caused by the heat exchanging medium andthe connected pipe, so the wall of the joint pipe must be madecomparatively thick. In addition, the joint pipe should have such alength that there is room for mounting tools between the flange of thejoint pipe and the outer side of the frame plate.

Another drawback is that a number of price raising machining operationsare required for the production of the known device. The said annularflange is thus welded to the joint pipe. Further, the frame plate has aconsiderable thickness, because it must be able to resist pressure fromthe compressed heat exchange package without bulging. For cost reasonsthe frame plate is made of an inexpensive material, and in order thatthe frame plate within the port will be protected against aggressivemedia, the stainless joint pipe is arranged such that it extends throughthe port to the inner side of the frame plate. The joint pipe must befixed within the port and, therefore, has a further flange welded at theend. The further flange is in turn welded to the inner side of the frameplate.

The said further flange must be given a certain thickness for reasons ofstrength. In order to avoid problems due to deflection of the heatexchange plate located nearest to the frame plate, an annular recessmust be milled around the port on the inner side of the frame plate forthe further flange.

A further drawback is that a device of the known kind in most countriesmust be approved by the authorities responsible for the issue ofexisting pressure vessel regulations.

To sum up, the known device requires a large consumption of expensivematerial and a lot of machining for its production, which leads to anexpensive final product.

The object of the present invention is to seek to eliminate theabove-mentioned drawbacks of the known device and, thus, to obtain aconnection device, which is as simple and inexpensive as possible.

This object is obtained, according to the invention, by a device of theinitially mentioned kind, which is principally characterized in that atleast at one port, between the frame plate and the annular tube flange,there if arranged at least one spacing member surrounding acommunication channel between the port and the interior of the tube, thetube flange, further, being connected with the frame plate by meansseparate from the spacing member in a manner such that the latter isclamped between the frame plate and the tube flange.

Sometimes, there are linings of stainless material, for instance rubber,plastics, stainless steel or titanium, arranged in the ports of theframe plate. At a port provided with a spacing member according to theinvention, the lining preferably extends even through the spacingmember, the latter being kept in a fixed position by means of flangesformed at the respective ends of the lining. Then, one of the liningflanges abuts the inner side of the frame plate, while the other liningflange is arranged between the spacing member and the tube flange.Hereby, the spacing member will not get in contact with the heatexchanging medium and, therefore, it may be made of an inexpensivenon-stainless material.

Since the lining has only the aim of protecting against aggressivemedia, it is preferably given a small wall thickness, for instance 1 mm.This avoids the need of an annular groove on the inner side of the frameplate for the lining flange.

The small wall thickness of the lining also means that its flanges maybe produced in a simple way by flaring out the ends of the lining bypressing.

In a plate heat exchanger with a lining extending through a port and therelated spacing member, the latter according to the invention may beallowed to have openings in its circumference portion extending aroundthe communication channel between the port and the interior of theconnected tube. Further, within the scope of the invention, the spacingmember may consist of several separate parts.

A device designed according to the invention is not concerned withexisting pressure vessel regulations.

The invention is explained more closely in the following with referenceto the accompanying drawing. In this, FIG. 1 shows a previously knowndevice in connection with a frame plate.

FIG. 2 shows a cross-section along the line II--II in FIG. 1, andconnected tube flanges.

FIG. 3 shows a frame plate provided with a spacing member according tothe invention.

FIGS. 4 and 5 show cross-sections along the lines IV--IV and V--V,respectively, in FIG. 3, and also tube flanges and linings connectedwith the frame plate.

The known device shown in FIGS. 1 and 2 comprises a frame plate 1 withtwo ports having a distance D between their centres, seen in the planeof the outer side of the frame plate. The distance D is smaller than thesum of the outer radii of two flanges supported by two tubes, which areconnected to the ports. Two joint pipes 2, 3, one 2 of which is longerthan the other 3, are inserted into the ports such that they protrude todifferent distances from the outer side of the frame plate 1. On theprotruding end portions of the joint pipes 2,3, there are welded annularflanges 4, 5, which are connected with correspondingly formed annularflanges 4a, 5a on the connecting tubes. The flanges 4, 5 of the jointpipes are provided with holes 10 intended for members connecting saidflanges with the tube flanges 4a, 5a. On the other end portions of thejoint pipes 2, 3, there are welded further annular flanges 6, 7. Theseare arranged in annular recesses 8, 9 around the ports on the inner sideof the frame plate 1 and are fixed thereto, for instance by welding. Thejoint pipes 2, 3 and their flanges 4-7 are made of a stainless material,whereas the frame plate, which does not get in contact with anyaggressive medium, is made of an inexpensive non-stainless material.

In FIGS. 3, 4 and 5, there is shown an embodiment according to theinvention,

FIG. 3 shows the outer side of a frame plate 11 of a non-stainlessmaterial, which may constitute the fixed or the movable frame plate of aplate heat exchanger. Two ports 12, 13 in the frame plate are situatedso close to each other that tube flanges 16, 17 of two connecting tubes(FIGS. 4 and 5) will not have room beside each other at the samedistance from the frame plate (compare FIGS. 1 and 2). Around the leftport 12 in FIG. 3, there is shown a removable spacing member 14 with anannular cross-section, forming a communication channel between the port12 and the interior of a tube to be connected with the frame plate.Around each port, and radially outside the spacing member 14, the frameplate 11 has threaded holes 15.

As can be seen from FIGS. 4 and 5, the tube flanges 16, 17 are connectedwith the frame plate 11 by means of stud screws 18, 19, which extendthrough holes 20 in the tube flanges 16, 17 and are fixed in the holes15 in the frame plate. Nuts, not shown in the drawing, are arranged onend portions of the stud screws 18, 19 extending from the holes of thetube flanges. In the ports 12, 13 there are inserted linings 21, 22 ofstainless material. At the port 12 where the spacing member 14 isarranged (FIG. 4) the lining 21 extends through the latter. The liningis provided with an annular flange 23, which is fixed between thespacing member 14 and the tube flange 16. The lining 21 is provided witha further annular flange 24, which abuts the inner side of the frameplate 11.

The other port 13 (FIG. 5) has no spacing member and has, therefore, alining 22 of a length corresponding to the thickness of the frame plate11. Also the lining 22 is provided with annular flanges at the ends, oneflange 25 arranged between the frame plate 11 and the tube flange 17,and one flange 26 abutting the inner side of the frame plate.

The spacing member 14 will not be in contact with the aggressive mediumbecause of the lining and may, therefore, be made of an inexpensivenon-stainless material, preferably the same material as the frame plate11.

Also other embodiments than the one shown in the drawing are conceivablewithin the scope of the invention. Thus, spacing members may be arrangedat both of the ports, having different lengths seen perpendicular to theouter side of the frame plate. Further, linings need not neccessarily bearranged in the ports. The means for connecting the tube flanges to theframe plate may also be constituted by screw bolts with heads having thesame function as the nuts at the previously described stud screws.

What is claimed is:
 1. A device in a frame plate for a plate heatexchanger, wherein two tubes provided with annular flanges and intendedfor heat exchanging media are connected with the frame plate such thatthe interior of each tube is in communication with a respective port inthe frame plate, the distance between the centers of the ports, seen inthe plane of the outer side of the frame plate, being smaller than thesum of the outer radii of the tube flanges, the tube flanges beingarranged at different distances from the frame plate, comprising atleast at one port between the frame plate and the annular tube flange,at least one removable spacing member surrounding a communicationchannel between the port and the interior of the tube, the tube flangesbeing connected with the frame plate by means separate from the spacingmember in a manner such that the spacing member is clamped between theframe plate and the tube flange.
 2. A device according to claim 1,wherein a spacing member is arranged only at one port.
 3. A deviceaccording to claim 1, wherein a spacing member is arranged at each port,the spacing members having different dimensions seen perpendicular tothe outer side of the frame plate.
 4. A device according to claim 1,wherein the spacing member has an annular cross section and forms thecommunication channel.
 5. A device according to claim 1, wherein themeans for connection of the tube flange with the frame plate are studscrews with cooperating nuts.
 6. A device according to claim 5, whereineach stud screw extends through a hole in the tube flange and isattached by one end to the frame plate perpendicularly thereto, a nutbeing provided on an end portion of the stud screw extending out of thehole in the tube flange.
 7. A device according to claim 1, wherein themeans for connection of the tube flange with the frame plate are screwbolts, which extend through holes in the tube flange and are screwedinto threaded holes in the frame plate.
 8. A device according to claim1, wherein a lining of a stainless material, for instance rubber,plastics, stainless steel or titanium, is arranged in each port.
 9. Adevice according to claim 8, wherein the lining extends through thespacing member and is provided with an annular flange, which is arrangedbetween the spacing member and the tube flange.
 10. A device accordingto claim 8, wherein the lining is provided with an annular flange, whichabuts the inner side of the frame plate.